#include "Model.h"
#include <stb/stb_image.h>

void Model::Draw(Shader shader)
{
	for (unsigned int i = 0; i < meshes.size(); i++)
		meshes[i].Draw(shader);
}

void Model::loadModel(std::string path)
{
	Assimp::Importer import;
	const aiScene * scene = import.ReadFile(path, aiProcess_Triangulate | aiProcess_FlipUVs);

	if (!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode)
	{
		std::cout << "ERROR::ASSIMP::" << import.GetErrorString() << std::endl;
		return;
	}
	directory = path.substr(0, path.find_last_of('/'));

	processNode(scene->mRootNode, scene);
}

void Model::processNode(aiNode* node, const aiScene* scene)
{
	// 处理当前节点的所有网格（如果有的话）
	for (unsigned int i = 0; i < node->mNumMeshes; i++)
	{
		aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
		meshes.push_back(processMesh(mesh, scene));
	}
	// 递归处理当前节点的所有子节点
	for (unsigned int i = 0; i < node->mNumChildren; i++)
	{
		processNode(node->mChildren[i], scene);
	}
}

Mesh Model::processMesh(aiMesh* mesh, const aiScene* scene)
{
	std::vector<Vertex> vertices;
	std::vector<unsigned int> indices;
	std::vector<Texture> textures;

	for (unsigned int i = 0; i < mesh->mNumVertices; i++)
	{
		Vertex vertex;
		// 处理顶点位置
		glm::vec3 vector;
		vector.x = mesh->mVertices[i].x;
		vector.y = mesh->mVertices[i].y;
		vector.z = mesh->mVertices[i].z;
		vertex.Position = vector;

		//法线
		vector.x = mesh->mNormals[i].x;
		vector.y = mesh->mNormals[i].y;
		vector.z = mesh->mNormals[i].z;
		vertex.Normal = vector;


		//纹理坐标
		if (mesh->mTextureCoords[0]) // 网格是否有纹理坐标？
		{
			glm::vec2 vec;
			vec.x = mesh->mTextureCoords[0][i].x;
			vec.y = mesh->mTextureCoords[0][i].y;
			vertex.TexCoords = vec;
		}
		else
		{
			vertex.TexCoords = glm::vec2(0.0f, 0.0f);
		}

		vertices.push_back(vertex);
	}
	// 处理索引
	for (unsigned int i = 0; i < mesh->mNumFaces; i++)
	{
		aiFace face = mesh->mFaces[i];
		for (unsigned int j = 0; j < face.mNumIndices; j++)
			indices.push_back(face.mIndices[j]);
	}
	// 处理材质
	if (mesh->mMaterialIndex >= 0)
	{
		aiMaterial* material = scene->mMaterials[mesh->mMaterialIndex];
		std::vector<Texture> diffuseMaps = loadMaterialTextures(material, aiTextureType_DIFFUSE, "texture_diffuse");
		textures.insert(textures.end(), diffuseMaps.begin(), diffuseMaps.end());
		std::vector<Texture> specularMaps = loadMaterialTextures(material, aiTextureType_SPECULAR, "texture_specular");
		textures.insert(textures.end(), specularMaps.begin(), specularMaps.end());
	}

	return Mesh(vertices, indices, textures);
}

std::vector<Texture> Model::loadMaterialTextures(aiMaterial* mat, aiTextureType type, std::string typeName)
{
	std::vector<Texture> textures;
	for (unsigned int i = 0; i < mat->GetTextureCount(type); i++)
	{
		aiString str;
		mat->GetTexture(type, i, &str);
		bool skip = false; // 标志变量，用于指示是否跳过纹理加载
		for (unsigned int j = 0; j < textures_loaded.size(); j++)
		{
			// 比较当前纹理路径与缓存中已加载纹理的路径
			if (std::strcmp(textures_loaded[j].path.C_Str(), str.C_Str()) == 0)
			{
				textures.push_back(textures_loaded[j]); // 如果路径相同，则使用缓存中的纹理
				skip = true; // 设置 skip 标志为 true，跳过后续加载流程
				break; // 找到匹配的纹理后，跳出缓存查找循环
			}
		}
		if (!skip)
		{   // 如果纹理在缓存中没有找到，则加载它
			Texture texture;
			texture.id = TextureFromFile(str.C_Str(), directory); // 加载纹理并创建 OpenGL 纹理对象
			texture.type = typeName;
			texture.path = str; // 存储纹理路径
			textures.push_back(texture); // 将新加载的纹理添加到当前网格的纹理列表
			textures_loaded.push_back(texture); // 同时添加到全局纹理缓存
		}
	}
	return textures;
}

unsigned int Model::TextureFromFile(const char* path, const std::string& directory)
{
	std::string filename = std::string(path);
	filename = directory + '/' + filename;

	unsigned int textureID;
	glGenTextures(1, &textureID);

	int width, height, nrComponents;
	unsigned char* data = stbi_load(filename.c_str(), &width, &height, &nrComponents, 0);
	if (data)
	{
		GLenum format;
		if (nrComponents == 1)
			format = GL_RED;
		else if (nrComponents == 3)
			format = GL_RGB;
		else if (nrComponents == 4)
			format = GL_RGBA;

		glBindTexture(GL_TEXTURE_2D, textureID);
		glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
		glGenerateMipmap(GL_TEXTURE_2D);

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

		stbi_image_free(data);
	}
	else
	{
		std::cout << "Texture failed to load at path: " << path << std::endl;
		stbi_image_free(data);
	}

	return textureID;
}